This project investigates the statistical problems involved in the measurement of experimental and clinical pain. (l) A study has been conducted to investigate the statistical technique used in deriving psychophysical measurements of pain. A report has been prepared for this work dealing with the interrelationship of sensory-decision-theory measures such as d' and Beta and nonparametrical measurement indices, such as p(A), Hodo's percent bias ad MacNicol's index of response bias, Beta. The investigation of this part of the work is completed. The report of this study is going to be presented at the 4th World Congress on Pain in l984. (2) A study of statistical quantification of the temporal characteristics of persistent, episodic pain such as migraine headache is currently being developed. A group of measurements for this type of pain has been selected for investigation. An external committee has reviewed the current state-of-the-art of the methodology for the measurement of pain. This meeting recommended that a full-scale symposium be supported to discuss various aspects of pain measurement problems.